1. Week: 13 Human-Computer Interaction
Waseem Iqbal
Assistant Professor
PhD-Scholar (Adaptive Interface for Mobile Devices in User’s Context)

2. Acknowlwdgement
Dr. Ibrar Hussain (Assistant Professor / HEC Approved Supervisor)
PhD. in Computer Science
Pervasive Computing Research Lab, Zhejiang University, China.
Carried out 6 months collaborative research work with HCI & SE group at University of Colorado, Boulder, USA.
Human Computer Interaction (Book)
3rd Edition by Alan Dix

3. Design rules
Designing for maximum usability – the goal of interaction design
Principles of usability
general understanding
Standards and guidelines
direction for design
Design patterns
capture and reuse design knowledge

4. Design rules
We require design rules, which are rules a designer can follow in order to increase the usability of the eventual software product. We can classify these rules along two dimensions, based on the rule’s authority and generality.
By authority, we mean an indication of whether or not the rule must be followed in design or whether it is only suggested.
By generality, we mean whether the rule can be applied to many design situations or whether it is focused on a more limited application situation.

5. increasing generality
Types of design rules
Principles
abstract design rules
low authority
high generality
standards
specific design rules
high authority
limited application
guidelines
lower authority
more general application
increasing authority
increasing generality

6. Principles to support usability
Learnability
the ease with which new users can begin effective interaction and achieve maximal performance.
Flexibility
the multiplicity of ways the user and system exchange information.
Robustness
the level of support provided the user in determining successful achievement and assessment of goal-directed behaviour.

7. Principles of learnability
Predictability
determining effect of future actions based on past interaction history
operation visibility
Synthesizability
assessing the effect of past actions
immediate vs. eventual honesty

8. Principles of learnability (ctd)
Familiarity
how prior knowledge applies to new system
guessability; affordance
Generalizability
extending specific interaction knowledge to new situations
Consistency
likeness in input/output behaviour arising from similar situations or task objectives

9. Principles of flexibility
Dialogue initiative
freedom from system imposed constraints on input dialogue
system vs. user pre-emptiveness
Multithreading
ability of system to support user interaction for more than one task at a time
concurrent vs. interleaving; multimodality
Task migratability
passing responsibility for task execution between user and system

10. Principles of flexibility (ctd)
Substitutivity
allowing equivalent values of input and output to be substituted for each other
representation multiplicity; equal opportunity
Customizability
modifiability of the user interface by user (adaptability) or system (adaptivity)

11. Principles of robustness
Observability
ability of user to evaluate the internal state of the system from its perceivable representation
browsability; defaults; reachability; persistence; operation visibility
Recoverability
ability of user to take corrective action once an error has been recognized
reachability; forward/backward recovery; commensurate effort

12. Principles of robustness (ctd)
Responsiveness
how the user perceives the rate of communication with the system
Stability
Task conformance
degree to which system services support all of the user's tasks
task completeness; task adequacy

13. increasing generality
Using design rules
increasing authority
increasing generality
Design rules
suggest how to increase usability
differ in generality and authority

14. Standards
set by national or international bodies to ensure compliance by a large community of designers standards require sound underlying theory and slowly changing technology
hardware standards more common than software high authority and low level of detail
ISO 9241 defines usability as effectiveness, efficiency and satisfaction with which users accomplish tasks

15. Guidelines more suggestive and general
many textbooks and reports full of guidelines
abstract guidelines applicable during early life cycle activities
detailed guidelines (style guides) applicable during later life cycle activities
understanding justification for guidelines aids in resolving conflicts

16. Golden rules and heuristics
“Broad brush” design rules
Useful check list for good design
Better design using these than using nothing!
Different collections e.g.
Nielsen’s 10 Heuristics
Shneiderman’s 8 Golden Rules
Norman’s 7 Principles

17. Shneiderman’s 8 Golden Rules
1. Strive for consistency
2. Enable frequent users to use shortcuts
3. Offer informative feedback
4. Design dialogs to yield closure
5. Offer error prevention and simple error handling
6. Permit easy reversal of actions
7. Support internal locus of control
8. Reduce short-term memory load

18. Norman’s 7 Principles
1. Use both knowledge in the world and knowledge in the head.
2. Simplify the structure of tasks.
3. Make things visible: bridge the gulfs of Execution and Evaluation.
4. Get the mappings right.
5. Exploit the power of constraints, both natural and artificial.
6. Design for error.
7. When all else fails, standardize.

19. HCI design patterns
An approach to reusing knowledge about successful design solutions
Originated in architecture: Alexander
A pattern is an invariant solution to a recurrent problem within a specific context.
Examples
Light on Two Sides of Every Room (architecture)
Go back to a safe place (HCI)
Patterns do not exist in isolation but are linked to other patterns in languages which enable complete designs to be generated

20. HCI design patterns (cont.)
Characteristics of patterns
capture design practice not theory
capture the essential common properties of good examples of design
represent design knowledge at varying levels: social, organisational, conceptual, detailed
embody values and can express what is humane in interface design
are intuitive and readable and can therefore be used for communication between all stakeholders
a pattern language should be generative and assist in the development of complete designs.

21. Summary Principles for usability
repeatable design for usability relies on maximizing benefit of one good design by abstracting out the general properties which can direct purposeful design
The success of designing for usability requires both creative insight (new paradigms) and purposeful principled practice
Using design rules
standards and guidelines to direct design activity

22. evaluation techniques
chapter 9
evaluation techniques

23. Evaluation Techniques
tests usability and functionality of system
occurs in laboratory, field and/or in collaboration with users
evaluates both design and implementation
should be considered at all stages in the design life cycle

24. Goals of Evaluation assess extent of system functionality
assess effect of interface on user
identify specific problems

25. Cognitive Walkthrough Heuristic Evaluation Review-based evaluation
Evaluating Designs
Cognitive Walkthrough
Heuristic Evaluation
Review-based evaluation

26. Cognitive Walkthrough The cognitive walkthrough is a usability evaluation method in which one or more evaluators work through a series of tasks and ask a set of questions from the perspective of the user. The focus of the cognitive walkthrough is on understanding the system's learnability for new or infrequent users
Proposed by Polson et al.
evaluates design on how well it supports user in learning task
usually performed by expert in cognitive psychology
expert ‘walks though’ design to identify potential problems using psychological principles
forms used to guide analysis

27. Cognitive Walkthrough (ctd)
For each task walkthrough considers
what impact will interaction have on user?
what cognitive processes are required?
what learning problems may occur?
Analysis focuses on goals and knowledge: does the design lead the user to generate the correct goals?

28. Heuristic Evaluation Proposed by Nielsen and Molich.
usability criteria (heuristics) are identified
design examined by experts to see if these are violated
Example heuristics
system behaviour is predictable
system behaviour is consistent
feedback is provided
Heuristic evaluation `debugs' design.

29. Review-based evaluation
Results from the literature used to support or refute parts of design.
Care needed to ensure results are transferable to new design.
Model-based evaluation
Cognitive models used to filter design options
e.g. GOMS prediction of user performance.
Design rationale can also provide useful evaluation information
GOMS is a specialized human information processor model for human-computer interaction observation that describes a user's cognitive structure on four components : "a set of Goals, a set of Operators, a set of Methods for achieving the goals, and a set of Selection rules for choosing among competing methods for goals.

30. Evaluating through user Participation

31. Laboratory studies Advantages: specialist equipment available
uninterrupted environment
Disadvantages:
lack of context
difficult to observe several users cooperating
Appropriate
if system location is dangerous or impractical for constrained single user systems to allow controlled manipulation of use

32. Field Studies Advantages: natural environment
context retained (though observation may alter it)
longitudinal studies possible
Disadvantages:
distractions
noise
Appropriate
where context is crucial for longitudinal studies
A longitudinal study is an observational research method in which data is gathered for the same subjects repeatedly over a period of time. Longitudinal research projects can extend over years or even decades.

33. Evaluating Implementations
Requires an artefact:
simulation, prototype,
full implementation

34. Experimental evaluation
controlled evaluation of specific aspects of interactive behaviour
evaluator chooses hypothesis to be tested
a number of experimental conditions are considered which differ only in the value of some controlled variable.
changes in behavioural measure are attributed to different conditions

35. Experimental factors Subjects who – representative, sufficient sample
Variables
things to modify and measure
Hypothesis
what you’d like to show
Experimental design
how you are going to do it

36. Variables independent variable (IV)
characteristic changed to produce different conditions
e.g. interface style, number of menu items
dependent variable (DV)
characteristics measured in the experiment
e.g. time taken, number of errors.

37. Hypothesis prediction of outcome framed in terms of IV and DV
e.g. “error rate will increase as font size decreases”
null hypothesis:
states no difference between conditions
aim is to disprove this
e.g. null hyp. = “no change with font size”

38. Experimental design within groups design
each subject performs experiment under each condition.
transfer of learning possible
less costly and less likely to suffer from user variation.
between groups design
each subject performs under only one condition
no transfer of learning
more users required
variation can bias results.

39. Analysis of data Before you start to do any statistics: look at data
save original data
Choice of statistical technique depends on
type of data
information required
Type of data
discrete - finite number of values
continuous - any value

40. Analysis - types of test
parametric
assume normal distribution
robust
powerful
non-parametric
do not assume normal distribution
less powerful
more reliable
contingency table
classify data by discrete attributes
count number of data items in each group

41. Analysis of data (cont.)
What information is required?
is there a difference?
how big is the difference?
how accurate is the estimate?
Parametric and non-parametric tests mainly address first of these

42. Experimental studies on groups
More difficult than single-user experiments
Problems with:
subject groups
choice of task
data gathering
analysis

43. Subject groups larger number of subjects  more expensive
longer time to `settle down’ … even more variation!
difficult to timetable
so … often only three or four groups

44. The task must encourage cooperation perhaps involve multiple channels
options:
creative task e.g. ‘write a short report on …’
decision games e.g. desert survival task
control task e.g. ARKola bottling plant

45. Data gathering several video cameras + direct logging of application
problems:
synchronisation
sheer volume!
one solution:
record from each perspective

46. Analysis N.B. vast variation between groups solutions:
within groups experiments
micro-analysis (e.g., gaps in speech)
anecdotal and qualitative analysis
look at interactions between group and media
controlled experiments may `waste' resources!

47. Field studies Experiments dominated by group formation
Field studies more realistic:
distributed cognition  work studied in context
real action is situated action
physical and social environment both crucial
Contrast:
psychology – controlled experiment
sociology and anthropology – open study and rich data

48. Observational Methods
Think Aloud
Cooperative evaluation
Protocol analysis
Automated analysis
Post-task walkthroughs

49. Think Aloud user observed performing task
user asked to describe what he is doing and why, what he thinks is happening etc.
Advantages
simplicity - requires little expertise
can provide useful insight
can show how system is actually use
Disadvantages
subjective
selective
act of describing may alter task performance

50. Cooperative evaluation
variation on think aloud
user collaborates in evaluation
both user and evaluator can ask each other questions throughout
Additional advantages
less constrained and easier to use
user is encouraged to criticize system
clarification possible

51. Protocol analysis paper and pencil – cheap, limited to writing speed
audio – good for think aloud, difficult to match with other protocols
video – accurate and realistic, needs special equipment, obtrusive
computer logging – automatic and unobtrusive, large amounts of data difficult to analyze
user notebooks – coarse and subjective, useful insights, good for longitudinal studies
Mixed use in practice.
audio/video transcription difficult and requires skill.
Some automatic support tools available

52. automated analysis – EVA
Workplace project
Post task walkthrough
user reacts on action after the event
used to fill in intention
Advantages
analyst has time to focus on relevant incidents
avoid excessive interruption of task
Disadvantages
lack of freshness
may be post-hoc interpretation of events

53. post-task walkthroughs
transcript played back to participant for comment
immediately  fresh in mind
delayed  evaluator has time to identify questions
useful to identify reasons for actions and alternatives considered
necessary in cases where think aloud is not possible

54. Interviews Questionnaires
Query Techniques
Interviews
Questionnaires

55. Interviews
analyst questions user on one-to -one basis usually based on prepared questions
informal, subjective and relatively cheap
Advantages
can be varied to suit context
issues can be explored more fully
can elicit user views and identify unanticipated problems
Disadvantages
very subjective
time consuming

56. Questionnaires Set of fixed questions given to users Advantages
quick and reaches large user group
can be analyzed more rigorously
Disadvantages
less flexible
less probing

57. Questionnaires (ctd) Need careful design Styles of question
what information is required?
how are answers to be analyzed?
Styles of question
general
open-ended
scalar
multi-choice
ranked

58. Physiological methods
Eye tracking
Physiological measurement

59. eye tracking
head or desk mounted equipment tracks the position of the eye
eye movement reflects the amount of cognitive processing a display requires
measurements include
fixations: eye maintains stable position. Number and duration indicate level of difficulty with display
saccades: rapid eye movement from one point of interest to another
scan paths: moving straight to a target with a short fixation at the target is optimal

60. physiological measurements
emotional response linked to physical changes
these may help determine a user’s reaction to an interface
measurements include:
heart activity, including blood pressure, volume and pulse.
activity of sweat glands: Galvanic Skin Response (GSR)
electrical activity in muscle: electromyogram (EMG)
electrical activity in brain: electroencephalogram (EEG)
some difficulty in interpreting these physiological responses - more research needed

61. Choosing an Evaluation Method
when in process: design vs. implementation
style of evaluation: laboratory vs. field
how objective: subjective vs. objective
type of measures: qualitative vs. quantitative
level of information: high level vs. low level
level of interference: obtrusive vs. unobtrusive
resources available: time, subjects, equipment, expertise